In his newest sci-fi blockbuster, After Earth, Will Smith plays a man who is incapacitated during a crash landing on earth some thousand years into the future and in order to survive he has to send his own son, played by his real life son Jaden Smith, on some perilous errand to retrieve a vital object through a landscape that has “evolved to kill humans.” Apparently, homo sapiens destroyed earth back in the 21st century and had to relocate to some other planet and earth isn’t looking to let bygones be bygones. At least that’s what I got from the 16 minutes of footage that was shown to the media prior to the press conference for the movie in Tokyo. It consisted of the two existing trailers spliced with three complete scenes from the movie. Smith is uncharacteristically stoical in the role. He treats his son as a soldier rather than his progeny, and that seems to be one of the hoary themes of the film, that these two will by the end learn to be father-and-son rather than commander-and-subordinate. That theme also carried over to the press conference, where the Smiths parodied their public image as a way of demonstrating that it wasn’t as serious as we might imagine.

No one sells himself as a movie star as aggressively as Will Smith, not even Tom Cruise, whose self-image is so circumscribed that he seems to have every response scripted. Smith wants you to know how much he enjoys his job and isn’t scared to wing it if it thinks it will endear him to the people who count, and here the people who count were the Japanese press, delighted to be privy to his every awkward ad lib. With Jaden he had a practiced straight man, and while their forced-funny banter was diminished by the dry translating of the interpreter, the audience relaxed immediately and didn’t seem to mind the lack of substance and Will’s penchant for pointless hyperbole. One guy sitting in back of me was a little too relaxed, letting out a studied guffaw at every gag.

“About two-and-a-half years ago, Jaden was working on The Karate Kid with Jackie Chan,” the elder Smith explained in response to the first question, “and I saw how much fun they were having working together, and I was jealous. I said, ‘Jackie, that’s my son.’ So I started thinking about a project that we could do together, and it started out in the present day about a father and son, and then one day I just had the inspiration of putting it a thousand years in the future, and from there I called M. Knight [Shyamalan] on his birthday and he said, ‘I don’t want birthday wishes, pitch me a movie,’ and I was just in the middle of it and I pitched him After Earth, and he loved it from that point.” It should be noted that Jaden Smith, who is now 14, made his feature film debut as Will Smith’s son in The Pursuit of Happyness in 2006, so it’s not like the pair had never worked together before. Maybe Will meant that it lookd like fun to do a totally frivolous piece of Hollywood product, since Pursuit was more or less serious, being about homelessness and all.

Or maybe it’s because Jaden has become more of an actor? “He’s gotten a lot more command and control of his emotional spaces,” Will said about his son’s skills. “When he was younger he had a very difficult time with emotional scenes because he would feel it so much that it took him a long time to get back to himself . What I saw on After Earth was that he was getting a lot more command of the trauma and emotion of being able to deliver a difficult scene without carrying it with him for the rest of the day.” In other words, he’s learned to turn it off, which is sort of a hallmark of Hollywood acting anyway, so I guess that means Jaden has arrived. As far as what the younger Smith learned about his father during the shoot, it had more to do with commercial exigencies. “I realize now how much he’s driven, and how serious he is about getting a movie done and how he wants it to be perfect because that’s what will be on the screen forever. You can never take it off, and all of us can see that.”

A different theme in the movie, environmentalism, brought out the platitudes, thus indicating there wasn’t much to ad lib when it came to the touchy subject of the fate of the earth. “Jaden’s generation is going to have a much more serious, much more difficult problem than our generation,” Will said, and then, catching his own seriousness, joked to the male reporter who brought the subject up, “You’re probably a little bit older than me, so it might be less of a problem for you.” Jaden, who had learned how to handle a press conference well by now, still wasn’t going to take any chances. “This movie is a big wake up call for a lot of people out there,” he said. “I really believe that after seeing this movie we can all make a difference.”

Jaden was honored more directly by Sony Pictures with the presence of several dozen junior high school students who had been bussed in just for the occasion. He jumped off the dias and ran over to the uniformed kids, high-fiving and hugging them, saying “how’s it going” in a loud voice that was spontaneous without being disruptive. He was learning fast from the master, and, in fact, one could often pick up a note of rivalry between father and son: Who would steal more hearts? More pointedly: Who would get the last word?

When one boy asked in English which scene was the “hardest” and which scene was the “happiest,” the Smiths concurred on the former, which was one of the scenes in the footage shown earlier, an argument between their two characters that ended with a typical bit of adolescent defiance. “As much as it’s acting you have to be careful about carrying the negative emotions,” Will said, belaboring the point. “After that scene, you get to the end of the day and as a parent get an overwhelming urge to put your costar on punishment.” However, the second part of the question flew over their heads until the emcee clarified that what they boy meant was which scene was the most “enjoyable” to do. Again they both agreed at the expense of the movie. The press was asked not to reveal too much of the plot, but for some reason nobody bothered to tell the Smiths that. “We were almost never together,” Jaden said. “And anyway there weren’t too many happy scenes, until the very end.”

Though some of the questions did try to focus on the film and one person actually seemed interested in knowing what M. Night Shyamalan’s contribution was (a concept called “ghosting,” apparently, which sounds like a Jedi Knight trick), Will inevitably hijacked the p.c. “So what was it like working with your father?” he asked in a stentorian announcer’s tone. Jaden, struggling to find a humorous egress from this potential cul-de-sac, kept his cool for as long as possible and went along with the joke, but after several questions he had to bring dad down a notch. “As you can see in the poster, I have the weapon, you don’t. I get to kill stuff, and you’re just watching me do it. I’m like the game and you’re the remote control.”

“That’s good,” Will said, more impressed than the media, who couldn’t make the right connections quickly enough. But dad got the last word anyway. “I mean, I was there. And I got most of the money.” It was the big laugh he’d been looking for all along.